ABSTRACT
The UK program on reed bed treatment systems is concentrating almost exclusively on beds planted with Phragmites australis, the common reed. The ultimate aim of any research program into reed bed treatment systems (RBTS) is to demonstrate the feasibility of such systems and to produce successful designs for their construction. Although this chapter concentrates on the hydraulics of RBTS, it is necessary to discuss the possible mechanisms of treatment that take place, because they define the objective of any design. Due to an oversimplified application of Darcy’s law, many early UK reed beds were built with a slope. It seems likely that all future UK reed beds will have level surfaces and level or very gently sloping bases. Reed beds with a surface slope generally have an area where reeds thrive and an area of poor growth due to excessive standing water at the outlet end or dry conditions at the inlet.
